"London's bass-baritone is a near-ideal Dutchman's voice. Its potent voice of the zealous intensity, harnessed to the boldness of his delivery, transmits a fearsome single-mindedness. Like Hotter, London imbues his tone with anguish, but unlike Hotter, he intermingles menace with pain....the portrait has such size, such granitic force, that magnitude in itself implements characterization....The bass-baritone is in superlative voice, and his instrument grows in power, steadiness and, above all, tonal purity throughout the afternoon. Like burning coals burning red, now white with heat, the firm tones which he pours into the climax of the duet with Senta are indeed worthy of legend....As Senta pledges faithfulness unto death, the soprano's triumph is complete. Is it danger that vibrates in those top tones and makes Rysanek so intriguing an artist, a heroine singing on the edge, abandon and exaltation captured in the cutting brilliance of her tone?"

- Paul Jackson, SIGN-OFF FOR THE OLD MET, pp.287-90

“In the many performances I have appeared in, there were many wonderful colleagues who had me in raptures. There were those with magnificent voices, or great musicians, wonderful actors or great personalities. But George London had it ALL. He was as impressive on stage as he was the wonderful colleague and friend in his private life.”

“George London was a dramatic and very expressive singer. In many rôles he sang like a demonic panther with a sound of purple-black in color. London was a singer favoring the drama in a piece, varying color to suggest shifts of mood. His acting on stage was described as overwhelming. The special magnetism of this artist is documented on his great recordings. Every rôle he sang was sung with utmost expression and unbelievable commitment, truly a singing-actor!”

- Andrea Shum-Binder, subito-cantabile

"The voice of the Bavarian tenor Karl Liebl was recognised while he was studying to become a school teacher. In 1945, after serving in World War II, he became a Jugendlicher Heldentenor at the Stadttheater of Regensburg. Here he sang, among others, Riccardo in BALLO, Radames and his first Wagner role: Siegmund. The first of his frequent appearances at the Staatstheater of Wiesbaden was in 1951, thereafter, he began to develop into a Heldentenor. From 1955 through 1959 he sang at the Cologne Opera including Huon in OBERON at the opening of the new house. From 1956-59 he was a member of the Staatsoper in Vienna, where he sang in premiere of MATHIS DER MALER by Hindemith.
From 1959 to 1968 he performed at the Metropolitan Opera (debut role: Lohengrin) in such roles such as Tristan, Walther von Stolzing, Erik, Loge, Siegmund, Siegfried, Parsifal and Herod in SALOME - in all, eight major roles in 57 performances. He died in 2007."